(0)Leopard Permissions issue
This is documented elsewhere, but since it took me a little bit of work to find a workable solution, and the chosen solution for me amongst many comments in various Apple Discussions threads, I thought I'd put a mention here.
The Issue:
For certain folders within my personal user folder, most notable my users sites folder (~/Sites) and various subfolders thereof, I no longer could save over my files. Coda offered me the option of authenticating with my admin password or replacing the files; finder mostly wouldn't allow me to rename or otherwise alter these files, short of deleting and replacing.
A quick trip to "get info" revealed that while I was the rightful owner of these files, the GROUP was set to "unknown" and had read-only access (sorry, I didn't have the foresight to take a screenshot before I fixed the problem). "Everyone" was set to have write access, but that part didn't seem to matter. From prior experience in Tiger, generally files of this nature are assigned to the group "staff", and would have write privileges. A solution after the jump...